here's a really old fart: Ralph Stanley (and the Clinch Mountain Boys) A Harldy Strictly Bluegrass staple.
I was lucky enough to be backstage at this year's HSBG and Ralph walked by and someone asked "Who's that woman?" heh.. When you are old enough, or young enough, you kinda lose your genderizing features. That's why really old drag queens work so well.
ETA: oops, my mistake, it's not Ralph Stanley's version that was used in the movie, but the Soggy Mountain Boys.